Heat radiator

ABSTRACT

A heat radiator includes a heat absorbing element, a heat radiating element, and a pump connected with the heat absorbing element and the heat radiating element to define a closed circuit. The pump circulates a refrigerant through the closed circuit. The heat absorbing element includes a heat-exchanging portion for transferring heat generated by a heating element to the refrigerant, a cover joined to a peripheral edge of the heat-exchanging portion to define a refrigerant flow channel therebetween, and one or more connecting members disposed within the refrigerant flow channel and having opposite ends joined to the heat-exchanging portion and the cover, respectively, to connect the heat-exchanging portion and the cover with each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat radiator for radiating heat froma heating element such as a semiconductor element mounted in anelectronic appliance such as a computer or the like.

2. Description of the Related Art

Japanese Laid-Open Patent Publication No. 2001-24372 discloses aconventional heat radiator, which is mounted in a notebook computer toradiate heat from a heating element in the computer.

As shown in FIG. 1, the heat radiator in the computer 50 includes a heatabsorbing element 52 attached fast to a heating element 54 mounted inthe computer 50, a pump 56 fluid connected to the heat absorbing element52, and a heat radiating element 58 fluid connected to the heatabsorbing element 52 and the pump 56, all connected in series to definea refrigerant circulating cycle. A typical refrigerant employed in thisrefrigerant circulating cycle is an easy-to-handle water-based one, andthe pressure inside the refrigerant circulating cycle is relatively lowof being approximately atmospheric pressure.

However, the heat radiator of the above-described construction is notsuited to the use of a high-pressure refrigerant such as afluorocarbon-based refrigerant, a latent heat effect of which iseffectively utilized to further reduce the heat resistance to enhancethe heat radiating performance. Because the pressure-resistant strengthof the heat absorbing element 52 is not taken into consideration, it islikely that the use of the high-pressure refrigerant may deform thesurface of the heat absorbing element 52 to which the heating element 54is joined, giving rise to a possibility of lowering the heat radiatingperformance.

SUMMARY OF THE INVENTION

The present invention has been developed to overcome the above-describeddisadvantage.

It is accordingly an objective of the present invention to provide aheat radiator having a heat absorbing element suited to the use of ahigh-pressure refrigerant.

In accomplishing the above and other objectives, the heat radiatoraccording to the present invention includes a heat absorbing element, aheat radiating element, and a pump connected with the heat absorbingelement and the heat radiating element to define a closed circuit. Arefrigerant filled in the closed circuit is circulated through theclosed circuit by the pump. The heat absorbing element includes aheat-exchanging portion for transferring heat generated by a heatingelement to the refrigerant, a cover joined to a peripheral edge of theheat-exchanging portion to define a refrigerant flow channeltherebetween, and at least one connecting member disposed within therefrigerant flow channel and having opposite ends joined to theheat-exchanging portion and the cover, respectively, to connect theheat-exchanging portion and the cover with each other.

The presence of the connecting member within the refrigerant flowchannel reduces the surface areas of the heat-exchanging portion and thecover, to which the pressure of the high-pressure refrigerant flowingthrough the refrigerant flow channel is applied, and also reduces theload applied to such surface areas, thus preventing the surface of theheat-exchanging portion confronting the heating element from lowering inflatness.

The cover is joined to the heat-exchanging portion by melting a brazingfiller material within a furnace. Although a high temperature inside thefurnace reduces the strength of the heat absorbing element, theconnecting member acts to maintain the strength of the heat absorbingelement above a predetermined level without deforming the surface of theheat absorbing element to which the heating element is joined.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objectives and features of the present inventionwill become more apparent from the following description of a preferredembodiment thereof with reference to the accompanying drawings,throughout which like parts are designated by like reference numerals,and wherein:

FIG. 1 is a perspective view of a notebook computer having aconventional heat radiator mounted therein;

FIG. 2 is a circuit diagram of a heat radiator embodying the presentinvention;

FIG. 3A is a front elevational view, partly in section, of a heatabsorbing element mounted in the heat radiator shown in FIG. 2; and

FIG. 3B is a section taken along line A-A in FIG. 3A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This application is based on an application No. 2003-277384 filed Jul.22, 2003 in Japan, the content of which is herein expressly incorporatedby reference in its entirety.

Referring now to the drawings, there is shown in FIG. 2 a circuitdiagram of a heat radiator R embodying the present invention. The heatradiator R shown in FIG. 2 includes a heat absorbing element 2, a heatradiating element 4, and a pump 6, all connected in series via piping 8to define a closed circuit. A high-pressure refrigerant filled in thisclosed circuit circulates through the heat absorbing element 2, the heatradiating element 4, and the pump 6 in this order.

FIG. 3A depicts the heat absorbing element 2 partly in section, and FIG.3B is a section taken along line A-A in FIG. 3A.

As shown in FIG. 3A, the heat absorbing element 2 confronts and isattached fast to a heating element 10 such as, for example, asemiconductor element mounted in an electronic appliance such as, forexample, a computer. The heat absorbing element 2 receives heat Qingenerated by the heating element 10 via a coating film 12 interposedbetween the heating element 10 and a heat-exchanging portion 14. Theheat-exchanging portion 14 is made of a material having a high thermalconductivity such as, for example, copper, aluminum or the like. Theheat Qin received by the heat absorbing element 2 is transmitted to thehigh-pressure refrigerant via the heat-exchanging portion 14. Thehigh-pressure refrigerant so supplied with the heat Qin is carried intothe heat radiating element 4, which is then cooled by a fan 16juxtaposed therewith. As a result of cooling by the fan 16, thehigh-pressure refrigerant exhausts heat Qout to the open air. Thehigh-pressure refrigerant having exhausted the heat Qout returns to thepump 6 again, thus forming a closed cycle.

A typical example of the high-pressure refrigerant is afluorocarbon-based refrigerant known as R134. When this refrigerant isused in a heat radiator of the type referred to above, the refrigerantcomes to range generally from 0° C. to 95° C. In this temperature range,a latent heat effect of the high-pressure refrigerant is utilized thatis brought about by a change in phase between a liquid phase and a vaporphase of the refrigerant, making it possible to realize a highheat-exchanging performance during the heat absorbing and radiatingprocesses and to reduce the heat resistance of the entire heat radiatorR. Also, in the above temperature range, the refrigerant pressurebecomes high enough to reach approximately 3 MPa and, hence, thepressure-resistant strength of the heat radiator R is important.

The heat absorbing element 2 includes, in addition to theheat-exchanging portion 14, a cover 18 joined to a peripheral edge ofthe heat-exchanging portion 14 to define a refrigerant flow channel 20therebetween, an inlet tube 22 joined to the heat-exchanging portion 14,and an outlet tube 24 joined to the heat-exchanging portion 14 on theside opposite to the inlet tube 22. The refrigerant is introduced intothe heat absorbing element 2 through the inlet tube 22 and dischargedtherefrom through the outlet tube 24. The cover 18 is joined to theheat-exchanging portion 14 by melting a brazing filler material within afurnace. Considering the properties of the brazing filler material, thetemperature inside the furnace is required to reach approximately 900°C. Accordingly, if both the heat-exchanging portion 14 and the cover 18are made of a like material such as copper or the like, thepressure-resistant strength of the heat absorbing element 2 considerablyreduces, and it is likely that the use of the high-pressure refrigerantmay deform the surface of the heat absorbing element 2 to which theheating element 10 is joined. If the flatness of such surface is notmaintained, the thickness of the coating film 12 on which the thermalconduction depends increases partially, resulting in an increase in heatresistance.

In the practice of the present invention, the heat absorbing element 2includes one or more (four in FIG. 3B) connecting members 26 disposedwithin the refrigerant flow channel 20 and having opposite ends joinedto the heat-exchanging portion 14 and the cover 18, respectively, toconnect them. Because the connecting members 26 receive the pressure ofthe refrigerant inside the refrigerant flow channel 20, the pressureapplied to the opposing surfaces of the heat-exchanging portion 14 andthe cover 18 that are exposed to the refrigerant flow channel 20reduces, enhancing the bending strength of the heat-exchanging portion14 and preventing the surface of the heat-exchanging portion 14confronting the heating element 10 from lowering in flatness.

Although the present invention has been fully described by way ofexamples with reference to the accompanying drawings, it is to be notedhere that various changes and modifications will be apparent to thoseskilled in the art. Therefore, unless such changes and modificationsotherwise depart from the spirit and scope of the present invention,they should be construed as being included therein.

1. A heat radiator comprising: a heat absorbing element; a heatradiating element; a pump connected with said heat absorbing element andsaid heat radiating element to define a closed circuit, said pumpcirculating a refrigerant through the closed circuit; and said heatabsorbing element comprising: a heat-exchanging portion adapted totransfer heat generated by a heating element to the refrigerant; a coverjoined to a peripheral edge of said heat-exchanging portion to define arefrigerant flow channel therebetween; and at least one connectingmember disposed within the refrigerant flow channel and having oppositeends joined to said heat-exchanging portion and said cover,respectively, to connect said heat-exchanging portion and said coverwith each other.